Details

Autor(en) / Beteiligte

• Chlot, Sara
• Widerlund, Anders
• Oehlander, Bjorn

Titel

Nitrogen uptake and cycling in Phragmites australis in a lake-receiving nutrient-rich mine water: a super(15)N tracer study

Ist Teil von

• Environmental earth sciences, 2015-10, Vol.74 (7), p.6027-6038

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Uptake and cycling of nitrogen (N) in the littoral zone of a lake-receiving nutrient-rich mine water located in Boliden, northern Sweden, was investigated. Stable isotope tracer solutions of super(15)N as NH sub(4) super(+) (NAM mesocosm) or NO sub(3) super(-) (NOX mesocosm) were added to mesocosms enclosing plants of common reed (Phragmites australis). The super(15)N abundance in various plant parts was measured at pre-defined time intervals over an experimental period of 22 days. During the course of the experiment, plant parts from the NAM mesocosms were significantly more enriched in super(15)N than plant parts from the NOX mesocosms. On day 13, Delta delta super(15)N values of the fine roots from the NAM mesocosms had reached +8220 ppt, while the maximum Delta delta super(15)N value in NOX roots was considerably lower at +4430 ppt. Using super(15)N values in macrophyte tissues present at the end of the experiment enabled calculations of uptake rates and % of tracer N recovered in the plant (%tracerNrecov). Maximum tracer uptake rates were higher for the NAM mesocosms (1.4 mu g g super(-1) min super(-1) or 48 mg N m super(-2) d super(-1)) compared to the NOX mesocosms (0.23 mu g g super(-1) min super(-1) or 8.5 mg N m super(-2) d super(-1)). Calculations of %tracerNrecov indicated that 1-8 and 25-44 % of added N was assimilated by plants in the NOX and NAM mesocosms, respectively. Hence, P. australis was more effective in assimilating NH sub(4) super(+), and a larger portion of the tracer N accumulated in the roots compared to the other plant parts. Consequently, macrophyte N removal is most effective for cold-climate aquatic systems receiving mine water dominated by NH sub(4) super(+). For permanent removal of N, the whole plant (including the roots) should be harvested.